AUSTRALIANS are feeling the pinch of more and more people every day, with ever-increasing commute times, packed buses and trains, lack of schools and unaffordable housing.

And with population growing at a rapid rate, with almost 400,000 additional people in the last year alone, experts have expressed fears the nation is headed for a fall and isn't prepared for the influx.

The populations of Melbourne, Sydney, Brisbane and Perth have expanded by nearly three million extra people in the last 10 years, with our nation expected to be a population of 40 million by the middle of the century.

Four Corners on Monday night delved into what a "Big Australia" would mean and the tough decisions that will be made if the population explodes as anticipated.

Cities such as Melbourne and Sydney becoming of the scale of global cities like London and Hong Kong. Picture: NASA

The investigation also revealed megacities are predicted to double their current size and our lack of preparation for such growth, how we got to this point, and if Australia needs a national population policy.

STATE POPULATION BREAKDOWN
Sydney is on track to hit a population of around eight million in the middle of this century.

Sydney’s population is set to soar by the middle of this century.

Perth will grow from just over two million to four and a half million.

Brisbane is projected to reach four million people - up from around up from 2.4 million.

"What we're facing now is a change in the face of our cities," Infrastructure Australia chief executive Philip Davies said.

"Cities such as Melbourne and Sydney becoming of the scale of global cities like London and Hong Kong.

"And then some of our slightly smaller capital cities, Perth and Brisbane, becoming in the future the same size as Melbourne and Sydney.

"So we need to up our game in terms of planning."

An aerial shot of Brisbane, downtown and river.

Former NSW Premier Bob Carr questioned what 'planning' would do to natural and beautiful spaces, referring certain methods to control population as creating a 'dystopia'.

"When you contemplate the eastern suburbs of Sydney, access to the beaches, which is a natural space, recreational space, what do you do?" Carr said.

"Do you have fences and turnstiles? When the population around Bondi, for example, reaches the sort of intensified level that means the roads are choked most days in summer, do you start to ration access to the coastal walking trails along the coast?

"And down the national park? Fences, turnstiles, online ticketing. I mean, that's the sort of dystopia that we can see coming at us through the mist."

FAR BEHIND ON PUBLIC TRANSPORT AND SCHOOLS

If the population grew, experts argued there would be no choice but to expand and build, especially when it came to public transport networks.

Our public transport systems are ‘catching up’ with the rest of the world. Picture: Christian Gilles

Co-ordinator general at Transport for NSW Marg Prendergast told Four Corners Aussie's reliance on cars would need to change.

"We're doing everything we can to put public transport as a real option, because single car drivers are just not going to fit on the road in years to come," she said.

"We can't build ourselves out of this growth. We actually need to manage demand better. We want people to travel earlier, to travel a bit later."

NSW is working on getting employers to do shift work hours so that the traffic load can be spread across the day.

But if Melbourne and Sydney are going to become cities on the scale of London and Hong Kong, Ms Prendergast said much bigger changes were needed.

State governments are also frantically finding a solution for the lack of schools, with Victoria estimating they would need to accommodate for 90,000 additional students over the next five years alone.

MIGRANTS BIG PART OF POPULATION OVERFLOW

Skilled migrant Madhumali Chandrasena was facing deportation back to Sri Lanka because of a mistake on her permanent residency application. Picture: AAP/Brenton Edwards

Population growth was a move encouraged by the Howard government, who urged parents to have more children.

But it was their immigration changes that created new visas to bring more migrants and skilled workers to Australia, taking off with the mining boom in 2006.

Recent figures show that 63 per cent of our population growth comes from immigration, and around 2.7 million people have been added to our population through migration alone since 2005.

Treasurer Scott Morrison dismissed Abbott's claims, saying: "the hit to the budget of that would be about $4 billion to $5 billion over the next four years."

The Federal Government has cracked down on one sector of the immigration program in the way of temporary visas.

Gabriele Favaretto working at Cafe & Cucina in Surry Hills. The government last year cancelled the 457 visa. The hospitality industry is one of the biggest employers of 457 visas. Picture: Stephen Cooper

The list of approved jobs for foreign workers is much shorter and it is harder for them to stay and become permanent residents.

While that is easing population overflow, on the other hand businesses are worried with a bulk of their employees on temporary visas.

Demographer Dr Liz Allen said migrants were vital for the work force to function properly.

"Migrants are filling a need. The jobs that Australians don't want or are not skilled for," she said.

"And more importantly, immigrants actually drive up demand."

WE'RE LIVING LONGER

Self-funded retirees from left Bernice Lee, 81, from Drummoyne, Roy Gould, 83, from Ashfield and Gerry McInerney, 83, from Haberfield at the Uniting Seniors Gym at Lilyfield. Picture: Jonathan Ng

By mid-century, Treasury forecasts say there'll be twice as many of us over the age of 65, with four times as many over 85.

"A mega trend for the next 10, 15 years is of course, the transitioning of the Baby Boomers," demographer Bernard Salt said.

"Five million Baby Boomers coming out of the work force, take their tax paying capacity out. "Then they say, well thank you very much, I'll have an age pension.

"I'll have pharmaceutical benefits and anything else that's going. That is going to a major issue to manage."

Clarence City Council Alderman Doug Chipman argued that a large older population put too much demand on health care systems.

"In the last 30, 35 years, real public health expenditure on people aged 75 and over per person has increased sevenfold. Seven times," he said.

"We can deal with that if we've got a strong economy and if we've got the workers who are paying the taxes.

"They're gonna pay for the older people in the future. So the quality of life of older people in the future is contingent upon the current and future labour force."

WHY DIDN'T WE PLAN FOR THIS YEARS AGO?

To put it frankly, it was just too difficult to plan for it.

Aerial shots of Melbourne CBD. Picture: David Caird

Kevin Rudd preached the idea of a Big Australia when he was in power, but the move was canned by Julia Gillard when she took over.

Demographer Liz Allen said that move showed it was too hard.

"It kind of signalled to me, as a demographer, that population was too hard. It was too divisive," she said.

"The anxiety in the groups that I was conducting at the time for Big Australia, was what's your plan here? You can have this bold pronouncement, but what's the pathway between where we are now, and where that's gonna be?" social researcher Rebecca Huntley said.

Since then, the projections are even higher than they were when Rudd was PM.

Houses in Melbourne.

"We've done an abysmal job. You know, there has been really no serious integrated debate around all the key factors that population growth brings to our economy and our national way of life," Australian Industry Group chief executive Innes Willoz said.

"It's the Australian way. We just roll along. We don't think too hard about these problems and suddenly we're at a point now where some of our cities are really starting to stress so it's becoming a big problem."

FEARS AUSTRALIAN WAY OF LIFE WILL BE OVER

Jack and Jayne Todd with their dog Jack outside their house. Data shows the most popular house has four bedrooms and is on 708sq m, suggesting the Great Australian Dream of a house on a quarter acre block is not dead. Picture: Tony Gough

The 'great Australian dream' is likely headed for an overhaul with the overwhelming population growth and demand for infrastructure.

Businessman Dick Smith said he saw "disaster" for the Australian "way of life" he grew up loving.

"Just near here, I used to go through here as a young boy, and there were lots of houses," he told the program.

"They are just around the corner there, they are gradually being knocked down.

"But that's where an Aussie family could live the Aussie dream, they could buy a house.

"You can't do that anymore. You're jammed like a termite in a high rise, or I say battery chooks."

But Australian Industry Group chief executive Innes Willox had a more broad, open minded approach at the feared death of the 'Australian dream'

"Not everyone wants to live in a quarter acre block. Not everyone wants to live miles and miles and miles from where they work, which is the inevitable consequence of this," she said.

"But what we do need to do is to be able to give people choice.

"Affordable, realistic choice and that should be the goal of our policymakers. It's an issue of planning and planners need to get it right so that we are able to accommodate the needs of the community."